In imaging systems having direct conversion detectors, binning may refer to the combining of detected charge onto one or more common readout channels, for example among adjacent pixels of the direct conversion detectors. A detector of the imaging system may be utilized to detect x-ray photons to be converted into an electrical signal representative of an image of a target. Flux rate may be defimed as a number of x-ray photons per unit area for an imaging x-ray beam. The detector counts the number of photons impinging thereupon to provide a count rate, which may refer to a counted number of photons impinging upon given pixel area per unit time. At higher count rates, a pixel having a predefined area may receive more photons per unit time which may result in a greater opportunity for pile-up. In such a situation, the chance for overlap of the signal pulses from the absorption of two or more photons may be increased. Pile-up may result in a loss of photon counting information and thus an unutilized and/or wasted x-ray dose. Pixels of the direct conversion detector may be divided into multiple subpixels of smaller area that may be served by individual charge integrating amplifiers, shapers, discriminators and/or counting circuits in order to increase the flux rate capability of the detector. The flux rate capability may be increased since each subpixel has a smaller area and therefore receives fewer photons per second at given flux rate and will thus count fewer photons per unit time, the count rate. The count rate capability may be increased roughly by the ratio of area of the subpixel into the original or whole pixel area. For example, a pixel divided into four subpixels may result in one fourth the count rate per subpixel as compared to the whole pixel, if charge sharing among subpixels is negligible. However, the subdivision of a pixel into multiple subpixels with smaller areas may also increase the amount of charge sharing. Small area subpixels also have a larger perimeter to area ratio. The percentage of the area where x-rays absorption will result in sharing of charge between neighboring pixels is increased as the pixel size is decreased. Charge sharing may result in missed counts, for example if the received charge level in two subpixels is below a discriminator threshold. Alternately, double counts from one photon event may occur if the received charge in two subpixels both exceeds the discriminator threshold. Miscounting therefore is a loss or degradation of information. Such a loss due to charge sharing may increase with finer subdivision of the pixel into more and/or smaller sized subpixels.
It will be appreciated that for simplicity and/or clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, if considered appropriate, reference numerals have been repeated among the figures to indicate corresponding or analogous elements.